4029 Counter

[Data888]

I've been messing around with digital electronics over the last couple
of days and I seem to have run into a problem.
I have a 5v power supply (basically built from the instructions here:
http://www.play-hookey.com/digital/experiments/logic_ps.html ), except I
used a DC plugpack, so I omitted the rectifier diodes.
I built a circuit to eliminate switch contact bounce using a 4049 (shown
here: http://www.play-hookey.com/digital/experiments/manual_pulser.html
), and connected the output to the clock of a 4029 counter.
I put 4 LEDs running through 1k resistors on the outputs of the 4029,
and when I turn the power on they seem to turn on randomly, but when I
push the button nothing happens.
I have the 5v supply going to the Vdd pin, the Vss pin grounded, the
UP/DN and BIN/DEC pins high (5v supply).
Any ideas what I've done wrong? Thanks

Nick

 

[gcd]

Hi,

a few things to check.
is CIN on the 4029 tied to GND?
is the PE pin tied to GND?
check that the ouput of the 4049 changes when you push the button.

but I think the biggest problem is that the 4029 cannot drive LEDs. It can
only output 0.88mA and can only sink 0.88mA (with 5V supply). Your typical
LED needs 5 - 10 mA minimum.

Ideally what you want to do is use an open collector buffer or inverter ( ie
7406) after the 4029 ouputs and use that to drive the LEDS.

Use a 300 ohm resistor in series with the LED between the output of the open
collector device and VCC, that will give about 8 - 10 mA through the LED.

and some hints here that may be of use:

http://www.sfu.ca/phys/430/TTLCMOStips.html

Hope that helps
Greg


"Data888" <kcinSPAMBLOCK@bigfoot.com.au> wrote in message
news:3F28DAD2.2020205@bigfoot.com.au...

I've been messing around with digital electronics over the last couple
of days and I seem to have run into a problem.
I have a 5v power supply (basically built from the instructions here:
http://www.play-hookey.com/digital/experiments/logic_ps.html ), except I
used a DC plugpack, so I omitted the rectifier diodes.
I built a circuit to eliminate switch contact bounce using a 4049 (shown
here: http://www.play-hookey.com/digital/experiments/manual_pulser.html
), and connected the output to the clock of a 4029 counter.
I put 4 LEDs running through 1k resistors on the outputs of the 4029,
and when I turn the power on they seem to turn on randomly, but when I
push the button nothing happens.
I have the 5v supply going to the Vdd pin, the Vss pin grounded, the
UP/DN and BIN/DEC pins high (5v supply).
Any ideas what I've done wrong? Thanks

Nick